1. Field of the Invention
The present invention relates to a scroll-type compressor, and, more specifically, to a scroll-type compressor in which oil is introduced from a suction port into the interior of a housing when the compressor is assembled.
2. Description of Related Art
A scroll-type compressor is a fluid displacement apparatus wherein a pair of spiral elements are engaged to each other at an angular and radial offset. Orbital movement between the pair of spiral elements creates fluid pockets that are moved inwardly and change in volume to compress a fluid sucked from a suction chamber to the fluid pockets. The compressed fluid is discharged from the fluid pockets to a discharge chamber.
For example, as depicted in FIG. 3, a known scroll-type compressor has a housing 10. Housing 10 includes a rear housing 101 and a front housing 100. Front housing 100 includes a large-diameter cylindrical portion 103 fixed to an open end of rear housing 101, and a small-diameter cylindrical portion 105. Rear housing 101 and front housing 100 are aligned coaxially.
Drive shaft 11 is provided on a center axis X of housing 10. Drive shaft 11 extends to the interior of housing 10 through small-diameter cylindrical portion 105 of front housing 100. Drive shaft 11 includes a small-diameter portion 11a surrounded by small-diameter cylindrical portion 105 of front housing 100, and a large-diameter portion 11b surrounded by large-diameter cylindrical portion 103 of front housing 100. Drive pin 12 is fixed to the end of large-diameter portion 11b. Drive pin 12 extends in parallel to axis X and at a position eccentric from axis X. Large-diameter portion 11b is rotatably supported in cylindrical portion 103 via needle bearing 13. Small-diameter portion 11a is rotatably supported in cylindrical portion 105 via ball bearing 14.
An electromagnetic clutch 15 is supported on the outer surface of small-diameter cylindrical portion 105, and rotates via bearing 15d. Electromagnetic clutch 15 has a pulley 15a that is connected to an external drive source (not shown) by a V-type belt (not shown), and a rotation transmitting plate 15c that is fixed to the end of small-diameter portion 11a. Drive shaft 11 is driven by the external drive source via the clutch mechanism.
A first scroll member 16, known as a fixed scroll member, and a second scroll member 20, known as an orbital scroll member, are disposed within rear housing 101. First scroll member 16 has a disc-like first end plate 16a that is disposed coaxially along axis X and fitted into rear housing 101, and a first spiral element 16b that axially extends into an interior of rear housing 101 a surface of first end plate 16a. A leg portion 16c is formed an opposite surface of first end plate 16a. The top surface of leg portion 16c is in contact with the inner surface of bottom portion 101a. First scroll member 16 is fixed to rear housing 101 by bolt 17 inserted into leg portion 16c through bottom portion 101a. The interior of rear housing 101 is partitioned into a suction chamber 18 and a discharge chamber 19 by first end plate 16a of first scroll member 16.
Second scroll member 20 is disposed adjacent to first scroll member 16 in rear housing 101. Second scroll member 20 has a disc-like second end plate 20a disposed along axis Y that is radially offset from axis x by an amount of rs, and a second spiral element 20b that axially extends into the interior of rear housing 101 on a surface of second end plate 20a. Further, second scroll member 20 has a ring-shaped boss 20c formed on an opposite surface of second end plate 20a. Axis Y of second end plate 20a is positioned eccentric from axis X by an amount of rs. Second spiral element 20b of second scroll member 20 engages first spiral element 16b of first scroll member 16 at an angular offset of 180 degrees.
A suction port 18a that communicates with suction chamber 18, and a discharge port 19a that communicates with discharge chamber 19 are provided within rear housing 101. Referring to FIG. 3, suction port 18a opens foward second spiral element 20bof second scroll member 20. Although second scroll member 20 moves according to an orbital motion, as depicted in FIG. 3, second spiral element 20b is located at a position near suction port 18a, such that suction port 18a is almost closed by the outer surface of second spiral element 20b. Such an alignment may be employed in a compressor for an air conditioner for vehicles so that the compressor size is reduced. Typically, oil is introduced initially into suction chamber 18 through suction port 18a and enclosed in housing 100 when the compressor is assembled.
An eccentric bush 21 is disposed rotatably in boss 20c via needle bearing 22. Eccentric bush 21 is formed as a cylindrical body having a relatively large thickness, and disposed coaxially with second end plate 20a. An eccentric through hole 21a extends in parallel to axis X, and is defined in eccentric bush 21. A counter weight 23 is fixed to eccentric bush 21. Counter weight 23 extends in the radial direction of eccentric bush 21. Drive pin 12 is fixed to the end of large-diameter portion 11b of drive shaft 11, and is inserted slidably into through hole 21a of eccentric bush 21. Pin 21b is fixed to eccentric bush 21 and connects eccentric bush 21 and counter weight 23.
A race 24 is formed as a ring plate, and is fixed to the end surface of large-diameter cylindrical portion 103 of front housing 100. A race 25 is formed as a ring plate and is positioned to face race 24. Race 25 is fixed to the side surface of second end plate 20a of second scroll member 20. A plurality of balls 26 are interposed between races 24 and 25. Races 24 and 25, and balls 26 form a ball coupling mechanism for preventing rotation of second scroll member 20 while allowing revolution of second scroll member 20.
In such a scroll-type compressor, balls 26 roll along a circular route as defined between races 24 and 25 that has about the same radius as the radius of revolution rs of second scroll member 20. Balls 26 may roll while being pressed against races 24 and 25. Consequently, second scroll member 20 revolves while maintaining a predetermined angular relationship relative to front housing 100 and relative to first scroll member 16.
When the scroll-type compressor initially is assembled, oil is introduced into suction chamber 18 through suction port 18a. However, if oil is introduced into suction chamber 18 when second spiral element 20b of second scroll member 20 is located at a position near suction port 18a, such that suction port 18a is about closed by the outer surface of second spiral element 20b, then oil may overflow from suction port 18a to the outside of the compressor. This overflow may occur because the oil does not completely enter into suction chamber 18 through suction port 18a. In particular, when oil is introduced at an increased flow rate, oil may overflow from suction port 18a to the outside of the compressor. In order to avoid overflows, oil is introduced into suction chamber 18 after the position of second spiral element 20b of second scroll member 20 is shifted away from suction port 18a by hand rotating drive shaft 11. Such a procedure consumes time, thereby reducing the productivity of the compressor assembling operations.